arrowood



' Dec. 23, 1930. M. WQARROWOOD Re. 17,908

' manger: AND lETI-IOD OF BURNING FlimjzzaenZZrr- Reis aued Dee-23,1930;

4 UNITED STAT MILTON W. ARROWOOD, OF GREENWICH,

ENGINEERS, 1Nc.,"or' WORCESTER, MASSACHUSETTS, a conroaa-rroN i 4PATENT- o nc-i;

coNNEc'rIcU'r, ASSIGNOR *ro UNIVERSAL l FURNACE AND ME'rnon or BURNING-FUEL Original No. 1,617,510, dated February 15, 1927, Serial No.490,529, filed August 8, 1921.

' reissue filed February 14,

'This invention relates in general to a mthd of and means for burningfuel, operating furnaces, and treating metals in furnaces, and while Ihave shown it in the present drawings as embodied in one of thepreferred forms in a melting furnace, itshould be understood that theprinciples thereof are capable of embodiment in furnaces used'for otherpurposes, such as annealing orheating furnaces, or furnaces as used forsmelting metals for instance.

My present invention may naturally be used I in all that general classof furnaces where the conditions ar'eless exacting than in the treatmentof metals, in fact, the invention is not only desirable, but a realnecessity in any furnace for whatever. purpose, where .com-

minuted, pulverized, atomized, or diffused fuels are burned in freesuspension. It is obviously not feasible, and is not considerednecessary, to illustrate all possible types of such furnaces where myinvention is useful and necessary for-efficiency. Y

It should be observed that while the invention herein relates, ingeneral, to a method and means for-treating metals in furnaces,

. it is, nevertheless true that certain of the features of my invention,as herein disclosed, particularly as relating to the regulation of thetotal quantity and of relative proportions of fuel'and air, and the evendiffusion of the fuel throughout the air, and also as to the metals.

regulation of the static, pressure and draft in" the furnaces, applyequally well to furnaces ,1 in general, irrespective of whether thefurnace at the time maybe used fortreating These featuresare, in fact,vital to. the proper regulation and control of fur naces when firing.comminuted,, pulverized, atomized, or diffused fuel, all of which may befired and burned in free suspension. My invention relates to the controlof firing and burning ofany fuel fired into the fur-.. naces. Theregulatoryfeatures of myinvent-ion, as herein disclosed,'have'not beenunderstood as applied to fuels burned-in a finely divided and diffusedstate in free suspension. My invention relates particularly to themethod and means of establishing and n'ulinta-ining accurate control,under all de- Application for 1929- Serial N0- 339,964. I H

sired operatingconditions with all such fuels,

when burned, either-severally or collectively with two ormore saidfuelsin an evenly diffused condition -in free suspension in combination with'the correctly. proportioned combustion air delivered to the combustionchamber with the said fuel or fuels as an evenly diffused combustiblemixture.

Both the quantity and relative proportions, as well as the evenness ofdiffusion ,of the fuel or fuels throughout the combustible are at alltimes underdefinite control when fed to furnaces, either severally orcollectively, on the improved method herein outlined,.and

it is'this method of securin and maintaining definite control of alltheji ring and burning conditions which is the essence of my presentinvention. When the total quantities of fuel or fuels and air, as wellastherelative proportions of the same, and the diffusion of the fuel orfuels throughout the air volume are regulated'and controlled asin mypresent invention, the various operating conditions of the furnace arealso brought under control, with the result that my invention bringsabout a great improvement in the burning of all fuels in the state ofadiflused mixture in free suspension. v I f M present invention bringsabout a Imar (ed increase in the efficiency of such firing operationswhere comminuted, 'pulver- I ized, atomized, or diffused fuels are fedand burned in free suspension within the said furnaces. For example, thetotal quantity of combustion gases produced under close regulation and,hence, the velocity of flow through the furnace, is"likewise closelycontrolled.

All of this, it is readily understod, is a distinct advantage in theoperation of furnaces burning diffused fuelmixtures in freesuspension,--as herein described 1 Prior to my invention theseprinciples have not heretofore been at all understood in obnnectionwithfurnaces using such fuels burned in, free suspensionin the treatmentof metals and, in'fact, these correct principles, which are the essenceof my present invention, have not previously been understood or appliedin any form of urnace ,,former1y used and fired with fuels burned infree suspension, either for metallurgical'orother purposes. 7 Owing tothe intense heating conditions required in the treatment of metals andthe necessity for relatively high temperatures, as well as therestrictions to particular types of'furnace construction customarilyused in the metals industries, it has not been possible. heretoforesuccessfully to treat metals with these fuels fired and burned in freesuspension. One purpose of my invention, therefore, is to make possiblethe eflicient treatment of metals when fired with such fuels by establishing the aforementioned control conditions-which make possibleeflic'ient combus-' tion and application of the resultingheat to themetals being treated. J I Without these control conditions it would beimpossible to secure the desired te1npera- .tures in the furnace, inview of the large amount of heat'lost up the stacks, exceptby theconsumption of a prohibitive amount of fuel.

It will be recognized that these principles operating so effectivelyunder the exacting conditions existing in the metals industries will beequally effective in the operation of furnaces 1n general where it isdesired to fire such comminuted, pulirerized, atomized, orv diffusedfuel, or fuels, severally or two or more collectively, to furnaces. Inother lines of activity operating conditions are not so exacting, andthere is 'no limitation as to the necessity of maintaining temperatureson the order of the maximum possible temperatures obtainable from fuelcombustion. 1y, others have been able to operate such furnaceswith-steam generating equipment andfor other similarly less exactingindustrial applications by resorting to specially desigried furnaces atconsiderable sacrifice in first cost, and, in many cases, also amaterial sacrifice in the efliciency of combustion and heat application.I

It has previously beenthe necessary custom in general for the operatorsof such furnaces to rely upon special and elaborate furnace designsand,'in most cases, they lrave had to employ furnaces of unusually largedimensions. One of the primary purposes. of the present invention is toavoid the necessity .of using siich specialand largevcumbersome furnacesand, in fact, to bring the firing and operating conditions under suchclose regu-r lation and control that fuels, whether comminuted,pulverized, atomized,. or in the gaseous forms, may be readily andefiiciently.

. fired, severally or two or more fired collectively, and burned in freesuspension, irrespectiveof the articular form or construction of thegiven mace. In other words, it is the urpose of the present invention tomake the ring of all the hereinbefore described'fuels oranyfuels burnedin freesuspension, independent of particular or special furnace con- 659struction-{relying solely upon the hereiendis- Formerclosed regulationcontrol of the firing and furnace conditions to secure the desiredresults that-iscomplete combustion'of the fuel, or fuels, under theconditions mostfavorable for utilizing the liberated heat mostefficiently."

In certain kinds of furnaces of this general character, andparticularlyin meltin'g furnaces, it' has been customary heretofore to provide a'hearth which is sloped to a depressed point where the taphole islocated.

As the result of this shape of hearth, the

solid charge of pig iron and scrap iron which n is piled upon the bottomof the hearth for melting purposes, is concentrated over the depressedportion of the hearth where'it assumes considerable depth, forming abarrier for the flame of burning fuel. It follows therefore that theflame cannot penetrate to any considerable distance into the base of thecharge and becomes concentrated to "a large degree upon and against theforward portion of the charge, while the remaining portions aresubjected to very little heat; The result 1 is that the melting of thecharge takes place very slowly and requires the expenditure of agreatamount of fuel; F urtherinore, the moltenl.metalrforms a deep poolin the deressed portioh, the bottom of which tends to ecome cooled'sothat in practice, it becomes necessary torun the furnace for aconsiderable period after the metal is all melted before it is allheated sufficiently for pouring purposes. 1 One of the primar entinvention as relating particularly to melting furnaces is to provide afurnace, the hearth of which will. be substantially level fromend to endand devoid of-depressions so ,as to provide a relatively shallow bath ofsubstantially uniform depth. This construc-. tion permits of a more evendistribution of the solid charge'over' the area of the hearth, with theresult-that a large area of the charge is exposed to the action of theflames, thusma terially facilitating and expediting the melting of thecharge and reducing the amount of fuel required for the melting.Manifestly, the molten metal in a shallow bath having a largetop'surface" exposed to theheat in 'the fifrnace can be thoroughlyheated much more expeditiously than the same quantity of metal in a deepool. Consequently, with my improved shallow bath furnace, the pouringmay be begun soon after the actual melting has been completed, therebyeffecting amaterial economy both in time and in :fuel.

To insure the flow of the molten metal from the hearth through the tapholes, the hearth is preferably slightly inclined 'tran'sversely eitherfrom one side to the other,'or pref erably as herein shown, is slightlyarched transversely so'that'the moltenmetal will flowto both sidesthereof, where it may be purposes of my pres-- the furnace in controlledproportions at low velocity and-under low pressure, and thecommunicating opening between the furnace, and the stack is so locatedand so proportioned with respect to the fuel pressure and the size ofthe stack is so proportioned that the furnace chambenis usuallymaintained under a slight static pressure and the products of combustionleave the chamber and are delivered from the stack at a low velocity.Instead therefore of drawing enormousrquantities of heat up the stack,the fuel is practically completely consumed in the furnace chamber sothat its heat units become effective upon the charge to be heated ormelted and a minimum of heat is lostthrough the, stack, thereby greatlyincreasing the efficiency of the furnace. This draftcontr'ol is equallydesirable in the. operation of furnaces imgeneral,

whether or not the furnacesmay be used-for the treatment of metals.' Thestack and the draft opening betweemthe furnace and the stack are'sodesigned as to favor a slight static pressure in the furnace, but byvarying the fuel delivery pressure, this fstatic'pressure may be changedto a substantially balanced draft or to an appreciable outlet draft i ifdesired. My invent-ion therefore provides for a wide range offlexibility in its opera:

tion to successfully meet various conditions to which it may besubjected.

Another feature of ny invention resides in the provision of means fordelivering the romminuted, pulverized, atomized, or dif fused fuel orfuels mix-ed with air and evenly diffused throughout the air to thefurnace in a turbulent condition, so that it or they swirl as a mass ofslow moving mixture over the surface of the charge so as to-more readilydistribute its heat thereto. The effectiveness of the burning mixture isfurther increased in the caseofn eltiiig furnaces by delivering itdownwardly .or in a downwardly inclined direction from the nozzleagainst the bath which results 'in a penetration of the flame into themass of loosely piled material forming'the charge on the hearth, therebycausing the flame to continue along the hearth at the base of the chargewhile the charge is in solid state, and also causing it to nnpmgeagainst the adjacent margin of the bath when .melted, thus producing amost effective heatmgaction.

Another object of" this invention is to in sure-that the fuel, whethercomminuted, pulverized, atomized, or diffused, is delivered to thefurnace in a {completely atomized difa fused condition, being evenlydistributed throughout all ofthe necessary combustion air and the entirediffused mixture. of the comminutefd, pulverized, atomized, or diffusedfuel or fuels, severally or two or more collectively, being deliveredin'a swirling turbulent condition to the furnace; while at the same timecomplete control is maintained of the quantity and relative proportionsof the fuel. and air as well as control of the static pressure and otherfurnace operating conditions hereiii described. Itshould be particularlynoted that the essential nature of the novelty of the invention in thispatent is the main tai ning' of a definite control of all factorsrelating both to-the firing and chemical control of the gaseous andslagdeposits in the furnace.

This includes not only the control of the v quantities of fuel or fuels,together with the control of the quantity of air, butsalso includes thegoverning of velocity and static pressure in the furnace as well as thechemical control of the ingredients in the burning mixture or mixtureswhich, in turn, gives control 'of-the chemical ingredients in thefinished product; provided, of course, that the initial quantities ofthe desired. ingredients in the product are proportioned properly whenmaking up the. raw batch of material going into the furnace.

v l Vhile it is apparent that the chemial control of metals is adesirable and novel feature resulting from thef accurate control of thequantity and relative proportions of fuel and air, it should not beunderstood that it is the purpose to limit this invention tometallurgical processes alone. The desirable gasc'ondit'onsestablished'by accurate control of the quantity and relativeproportions of comminuted, pulverized; atomized, or diffused fuel orfuels, and combustion airdelivered in turbulent condition at lowvelocity are fully as effective in many other industrial applications asthey are in "metallurgical furnaces. It is obvious that such regulationis highly desirable in any furnace as tending to conserve the totalquantity of heat' and control the rate of heat liberation so as tosecure maximum efliciency.

A further object of my invention is to provide a" furnace in which thefront bridge wall isspaced a limited distance from the front Wall of thefurnace chamber, the for'-' ward end of the hearth between these wallsbeing provided with a masonry floor inclined downwardly from the frontwall to the bridge wall sothatany slag deposited on this portion of thehearth will drain freely into the bath. In-order however to relieve thebath from an accumulation of as much slag as possible, this floor isprovided adjacent the front wall and immediately beneath the point ofdelivery of the fuel into the furnace with a depressed pocket. Since thefuel is delivered at-low velocity, the flame formation pocket.

occurs near the front wall and that slag which results from the initialflame forma tion drops immediately intothis pocket from which it may beremoved at intervals through cleaning doors communicating with the Thisconstruction eliminates to a large extent that portion of the-slag whichis particularly in urious to the brick work ofthe bath and therebymaterially reduces the cutting in of the side walls of the furnace atthe slag line which has heretofore been a principal cause of brickrepairs. The

corrosive action upon the brick walls is further reduced by the factthatthe combustion in my improved furnace is rapid and complete instead ofprogressive throughout the length of the furnace, thereby causing animproved gas condition within the furnace which diminishes thedeteriorative effects upon the brick work and reduces the chemicalactivity of the walls.

Another and important feature of my in- 'vention resides in the factthat where the" proportions of the several ingredients of a charge aresubstantially correct, by mixing with the comminu-ted, pulverized,atomized,

or'difi'used fuel or fuels just sufficient air to support completecombustion, or, in other words, providing a neutral flame; bydelivei'ing this mixture at low velocity into the, furnace so that thecombustion is speedy and complete; by directing the burning mixturedownwardly against the bath; and by controlling the pressurewithinthe'furnace, an extremely high, intense and penetrating heat isproduced, which quickly melts the charge Without burning out as large a.percentage of the silicon and manganese as has heretofore been burnt outwith other methods of firing. The result is that the furnace chargemaycontain a much larger proportion of cheap scrap metal and acorrespondingly less amount of expensive iron than customary,

thereby reducing the cost of the charge while still producing malleablemetal of the desired composition.

The control of the combustion conditions which may be done so as toproduce a neutral or oxidizing, or a reducing flame, as desired,

is obviously a vital factor in the operation of all furnaces in generalwhere a fuel-or fuels are to be burned in free suspension, as hereindescribed. Even in the case of V furnaces under boilers or steamgenerators, for example, these control features arestill 'of vitalimportance, as they make possible the inost efficient combustion of thefuel, and tend to protect and conserve the furnace linings and heatingsurfaces. r

And it obviously follows as a corollary of thereby be modulated to meetthe requirethe relative bath slag upon the furnace f the matter of theforegoing paragraphs that regulation of the relative proportions of fueland air admitted through the burners will vary the character of theflame which may 'ments of the charge. For instance, if the proportionsof the carbon and silicon, manganese and sulplnirconstituents be toohigh,the proportion of air in relation to the fuel may be increased toproduce an oxidizing flame.

On the other hand, by decreasing the propertion of air a reducingflame'can be secured,

While, asabove, if the batch is properly proportioned, as it should be,a neutral flame is used which will neither reduce norincreaseproportions of the charge in-' gredi'ents. I

Still another object'of the invention is the provision of means wherebythe direction of dischargeof thefuel mixture into the furnace may beregulated and controlled so that it may be directed downwardly upon themasonry floor in front of the bridge wall, or may be directed over thebridge wall into the forward end of the bath, or may be directed towarda 'point in the bath more remote from its front end, as desired, thusproviding for flexibility in the furnace operation so that it may beaccommodated to various requirements and rendered highly efficient underall conditions.

It will be seen that this flexibility in con-- trolling not only thechemical character, but the direction in which the flame is projectedinto the furnace, is desirable in furnaces in general, where, forexample, it may be necessary or advisable to deflect the flame in adownward or otherwise specified. direction in order to. avoidimpingement against'refractory walls, radiant heat superheaters, or forother necessary and sufficient reasons.

Vhile in many cases it is desirable to point I thdflame in a downwarddirection and to control the angularity of discharge with reference tothe horizontal axis of the furnace, it should be-understood that thenumerous other desirable features of my present invention, and theinherent advantages ofits operation are not to be limited solely to thedownward projection ofthe flame. It is obvious that ion liq

all those features. of the invention'relating to the control of thetotal quantity and relative proportions of fuel and air and theresulting control ,of' the chemical condition of the gases inthe'furnace are present in the i operation of my improved furnace,irrespective of the angularity at which the flame is discharged. Theseand other similar advantages, t-herefore,are not to be in any senserestricted to the use of a flame discharged at a downward angle. 7

On theother hand, it is equally obvious that in many operations andespecially in the melting of malleable iron, and also to some I extentin the smelting of metals the downward direction the fiame and itsimpingement' on the bath .must necessarily involve decided operating.advantages which are equally as essential parts of my present inventionas is the other chain of advantages relating to and hinging about thecontrol of the quantity and relative proportions of fuel and air and,hence, the chemistry control and gas velocity control of the furnace.

It will be observed that one class of improvementsin the presentinvention relates and is applicable to all that class o'f furnaces ingeneral wherein the specified control conditions as to quantity,proportions, chemical constituents of' the gases, velocity andcontrolled draft pressure are always of necessity present when andwherever there is employed a burner capable of delivering acompletelyand evenly diffused mixture in a turbulent condition at relatively lowvelocity, ahd in all respects under complete control, such as is hadwhen using one of the preferred forms ofburners illustrated anddescribed herein. While the preferred burners; as-illustrated, areentirely capable of establishing the conditions precedent to thesuccessful working of this invention, it is entirely possible thatburners of other types may also be capable of establishing the necessaryconditions of turbulent firing under control, as herein described. It isnot desired, therefore, to restrict the invention to any particularburner structure, but it should be understood that any burner or feeddevice capable of establishing the conditions of operation as describedmay be satisfactorily employed in carrying out the improved method offurnace operation as embodied in the present invention.

Another class of advantages of the present invention relates moreparticularly to the control of chemical ingredients in the metal ormetals where same arebeing. melted or where ores are being smelted inorder to pro duce metals. It is readily seen that the herein describedadvantages resulting from the condition wherein the; chemistry of thefurnaces is at all times under accurate control, both as to thecombustion gas es andvthe slag or ash produced, while reactingvariously'in different types of furnaces, nevertheless at all times makepossible a definite improvement in operation. As pointed out elsewhere,one improved result has to do with the avpiding of rapid deteriorationon the refractories. This result, of course, is equally desirable in anyand all types of furnaces, part ofthe containing Walls of which consistof refractories and this, in effect, means practically all furnaces,inasmuch as few, if any, furnaces or combustion chambers are properlyconstructed Without the use of refractories, at least to some extent.

Another manner in' which the advantages I inherent in complete chemicalcontrol of operations are made manifest is in the control of chemicalingredients necessarily required in certain metals when melted or,smelted in order to produce the desired character of product. Again, forexample, in the case of steam boilers this same desirable completechemical control of gases and slag formation manifests its decidedadvantage in such mat-1 siderable percentages -of sulphur can beburnedwith immunity when the methods and means constituting the presentinvention are brought into play. Thus, for example, the sulphur is socompletely. and instanteously burned that the usualdeleterious efiect'sexperienced on heating surfaces and uptakes of the boilers are almostentirely eliminated. It is manifestly impracticable to catalogue all ofthe operating advantages resulting from the decided improvements ofmethod involved in the present invention, but it is be-\ lieved thatthese examples sufficiently illustrate the very decided improvement inoperation that is possible where full chemical control isestablished. Itshould be understood that such control is only possible Where the.

so operated in conjunction with the furnace form and draft regulation asto bring about,

through the combined operation of a suitable burner and furnace, theconditions of velocity, draft, and chemical control herein described.

Other objects and many of the inherent advantages of my invention shouldbe readily appreciated as the same becomes better understood byreference to the following descri tion, when considered in connectionwitht e accompanying drawings. 7

Referring to the drawings: Fig. 1 is a longitudinal sectional Viewthrough a furnace embodying my invention; Fig. 2 is a transversesectional view through the line 2-2 of Fig. 1 ;'and. I Fig. 3 is anenlarged sectional view through the delivery end of the mixer burner;

Referring now to the drawings more in del tail, it will be observed thatmy improved furnace comprises an enlongated chamber uninterrupted fromend to end but comprising two portions, namely: the rear portion inwhich the material to be heated 1s placed, and which may be consideredasa heating cham- --ber, and the forward portion where initialcombustion of the fuel begins and is prac tically completed and whichmay be considered as a combustion chamber. The furnace chamber as awhole comprises the front wall 5, rear wall 6, and the roof 7 all ofwhich are constructed of fire brick in & well known or preferred mannerand bound together by I suitable tie rods 8 cooperating with buck stays9. The bottom of'the chamber is provided with. a bridge wall 11extending upwardly into the chamber a limited distancc,-this bridge wallbeing spaced alimitcd distance from the front wall -5 and the spacebetween these walls being filled in and provided with a masonry floor 12which is inclined downwardly from its front edgetothe top of the bridgewall, The foundation 13 of the I furnace disposed rearwardly of thisbridge wall may be of suitable construction suitably covered inannealing or other heating furnacesgbut'for melting furnaces, such as Ihave hereinillustrated, this'foundation is covered by a sand bedltforming the hearth which is substantially levelfrom end to end insteadof having a' deep depression between its ends, as has'heretofore beencustomary.

This bed is-adapted toaccommodate a bath? 15 of molten metal which isrelatively shallow andof substantiallyequal depth from for aconsiderable distance to facilitate end .to end, although in practicethe rear portion is slightly sloped from rear to front of metal tothetap openings a-nd'to decrease the depth of the bath toward the rearof the furnace where the heat .is less high. This substantially levelhearth permits a substantially even distribution of the solid chargeover the area of the hearth and consequently the melting flame, insteadof encountering a deep barrier to the bottom" of which it would beunable to penetrate, is caused to impinge against a large area and .topenetrate the charge of loosely piled solid material and swirl along thebottom ,of the charge so as to most effectively deliver its heat units"to the charge and reduce the melting time to is scarcely apparent inFig. 1.

a minimum. 'In practice the material will be piled somewhat igher atthe;front end of the pile than it is in the rear of the chamber so thata larger quantity will be subjected'to the maximum lieat'mea-r theforward end of the hearth. The decrease 'in depth of the bath towardtherea-r end cor-' responds approximately to, the decrease intemperature and pressure of the products.

of combustion as they approach the rear end I of the chamber. Because ofthe reduced scale I of the drawings, this-decrease of bath depth For theurpose of holding the hot prodnets of combustion down against the bath,the

roof 7 is inclined downwardly toward its rear end, vand furthermore, theoutlet opening from the furnace to the stack and also the top of therear bridge wall are disposed only slightly above the level of the bath.The entirestructure therefore, is conducive to the most completetransference of heat from the products of combustion to the bath and toa high degree of furnace efficiency.

.In order to facilitate the withdrawal of the molten inetalfrom thebath, the floor thereof is preferably 7 slightly convex 1ntransversecross section, as will be apparent from Fig. 2. This upward arching" ofthe floor is adapted to causethe metal to flow to the sides of the bathfrom which it may be drawn of: through one or Inore tap holes 16 locatedat each side of the furnace. Should.

it be preferable to draw the entire charge from one side of the furnace,the lmthfioor, instead of being transversely arched, nlay be slightlyinclined from one side to the other so as to deliver the molten, metalto one side of the furnace.

The furnace may be charged through doors oropenings formed in the sidewall or through the roof, which may be equipped with removable bungs, asis customary in reverberatory furnaces. In this instance, I

have shown for purposes of illustration, the

side wall provided with a plurality of charging doors 18, such as arecustomarily em ployed in open hearth furnaces and through Which the pigand scrap 1ron and other 1ngredients of the charge may be introduced,flOW unto the chamber and distributed over the hearth.

In certain smelting furnaces it is necessary to control the temperaturewithin rather narrowly restricted limits, and also the character .ofgases must be under control of the operato r,

as otherwise with excess temperature and perhaps, at the same time anexcess of oxygenin the gases, theretwill be a-large loss of metal byoxidization and under certain conditions vthe smelting action, ormelting of the metal from the ore may be greatly impeded, due to thepossible excess formation of slag and lack of fl idity in same.

- T en again, in the case of smelting certain metals, a relativelyslight inc'reaseof temperature may, as 1n the case of zinc, for-example,cause a vaporization of the metal and a very large loss by waste due tosuch vaporized metal escaping with the stack gases. It

is believed that without further explanation or illustration sufficienthas "been stated to make plain the fact that very close control isnecessary, in all smelting furnace ,opera; tlons, so that the improvedfeatures of my present'inventlon are most practicable to all suehfurnaces,.and indeed may be said to be almost a prerequisite to nomic'aloperation.

successful. and eco- I Where the furnace is used merely for heatingingotsor bundles of metal, as in the furn ace commonly known as pile andboard fu1'- nace, the 'wall may be-eliminated and, if -desired, thefloormay be' nade practically level.

This floor may be constructed of specialrei'ractory-sand, asin thecaseoffthe'melting furnaces or other convenient refractories may be used, ifdesired. In'case the floor is made level, it will be necessary to cleanout the slag accumulation at perlodic intervals. It 1s,

therefore, generally preferable to slightly incl ine the floor in theseheating furnaces in the manner already explained for melting furnaces inorder that the slag may flow along the incline to the tap holes, whichmay be located on one or both sides of the furnace in the same manner asfor the melting furnaces. ()ne of the distinct advantages of myinvention in this respect lies in the fact that the flame produced underthe conditions of con trol embodied in the present invention is of suchcharacter and intensity as makes possiproducedat the point of flameformation, it

willlbe apparent that this slag will drop directly into the pocket 19where it. is collected and procluded from entering the bath. 1

have found that the separation of the slag produced at the point offlame formation of ble the formation of high oxide slag compounds, whichare more fluid than the low oxide compounds generally formed under lessfavorable conditions and, hence, it is pos-- sible to remove the bulk ofthe slag from the. furnace floor through the tap holes. In the previousoperation there has always been considerable difiiculty owing to thestiff natill - embodied ture of the low oxide slags, and the temperatureand chemical conditions setup in carrying out mypresent inventionovercome this serious operating condition. It will be seen, therefore,that the construction, as illustrated in Figures 1 to 3, is entirelysuitable for all such heating or reheating furnaces, but it, willreadily be seen that the improved principles of my inventioh mayfurnaces" having various modifications from the structure illustrated,and it is not the intention to restrict the method of this invention tothe particular structure.-

\Vhere it is desired to anneal metals directly, as in the heat treatmentof billets, rods, sheets, plates, etc.', the furnace as shown isentirely suitable, but again the principles of .my'invention are broadlycapable of being in furnaces of modified structure.

If the metals that are to be-subjected to annealing treatment are packedin large metal pots,.as is commonly done in the case of tin plates,and/or malleable castings, the furnace as illustrated in Figures 1 to 3,may still be employed, but as a matter of convenience in charging thefurnace a'modified construction is preferred. Special charging machinescapable of carrying large pots full of material are mostconvenientlyplaced in these ovens where the entire end consists of removable doors.

Referring again to the melting operation,

'it will be observed from Fig. 1 that the level of the bath is below thetop of the, masonry floor 12 and the upper edge of the bridge wall, sothat any slag which is deposited on this floor, above the level of thebath will drain freely into the bath. Adjacent the frontwall 5 the floor12 is provided'with a pocket 19 disposed immediately beneath thedelivery openings 21 through which the likewise be applied in gases andthe fuel mixture, and the elimination of this speedy and completecombustion of the-fuel which improves the gas condition in the fun nacechanges the chemical character of the. bath slag as well as reduces itsquantity, with the result that the corrosion of the brick work at theslag line is materially reduced, thereby' diminishing the necessity forrepairs to the furnace. The slag collected in the pocket 19 may becleaned out at intervals through cleaning doors 22 located in the sidewalls of the furnace at each end ofthe pocket. With controlledcombustion conditions as embodied in this invention theduantityncharacter and chemical composition of the combustion gases ismaintained practically constant on a given furnace. Since-combustion. iscomplete and the resulting gases are. inert the chemical conditionsinthe gases' are highly favorable to avoiding contamination or FIZ- juryto the product or to to the heating surfaces, or to the metal surfacesof pots, as in annealing processes. In previous practice there hasalways been considerable loss or damage in these varions directions, dueto irregular operation and 'iilso due to varying temperaportion from thebath coupled with the.

the furnace walls or as in steamboilers,

tunes and varying chemical conditions in the slag on the surfaces ofrefractories,

and especially in many cases due to excess oxygen owing to unbalancedcombustion conditions. This oxygen not only combines or burns out aconsiderable part of themetal,

but is also an active agent which, it may be said, is seeking to destroywhatever chemical elements it may encounter, and in the smelting ofmetals, for example, thc oxidizing of metals may even be a more seriousloss than that encountered in the above described melting operations.Without further explanm tion, it is complete chemical control of gasesand slag conditions inthe furnace as established in my present inventionis of the greatest importance;

I have shown in the present installation somewhat. diagrammatically, apreferred type of burner mixer, the general construction of which isdisclosed in U. S. Patent No. 1,855,444, granted October-12,1920, andthe preferred specific construction in. my cobelieved that theattainment of It.

, pending application,Serial'No. 299,833, filed May 26, 1919, now PatentNo, 1,474,613. In

this type of burner, thepowde'red coalis de-. livered from a hopper23tl1rough a worm screw easing into a mining cylinder 25 to which airunder pressure is delivered through a supply pipe 26. The fuel underpressure mixed with-air is then conducted through a connection 27 to themixer proper 28 to which additional air under pressure is suppliedthrough a pipe 29. q

After being thormxghly mixed with air in this mixer, the fuel isdelivered through. a tapered downwardly inclined conduit 31 into theforward end of the furnace chamber. The shape of this conduit causes themixture I of fuel and air to be delivered in a turbulent;

swirling condition and since the mixer is of,

the low velocity type, this turbulent supply of fuel continues afterignition in a swirling .mass'through the furnace in a -condition whichis-most favorableto the transference of its heat tothe charge in thefurnace.

It'will be noted that the delivery of the combustible mixture is in 'adownwardly oblique direction, but the vertical direction of dischargemay be varied'and controlled by means of a controlling plate ordamper 32located in the nozzle 33.0f the burner. This"controllingplate,which maybe made of sheet iron or suitable material, is pivotally supported upona transverse bearing rod 34 which may be equipped at one end with ahandle 35 or other means by which the position of the plate may beadjusted to any point intermediate the full open position shown'infulllinesin Fig. 3 and the full closed position shown in dotted linesinaid figure.

Any intermediate position bet een the two positions shown will vary thedirection of' discharge ofthe combustible mixture spthat it may bediverteddownwardly upon the floor 12 or -over the edgezof the bridgewall into the bath or into the bath at 'a point more. remote .from thebridge wall depending. on

the position. of the plate which is, of course,

adjusted 'to metthe requirements of. the

most instances be suificient charge and the condition under which thefurnace is being used. For purposes of bolding the plate in anyadjustedposition, I have. provided a sector member 36 having provi- "sion'sfforcooperativelyengaging the handle 35to hold it inanyfiiadjustedposition.-

l \Vhileone or a series; of bur11ers for-.f supplying fuel to thefurnace may be employed, depending on the size of the furnace and thesize of the burners, I have/shown in the pres entinstance; as willapparent from Fig. 2 two burners having theirdelivery nozzles located inspaced relation in the front.

wall 5. 1 p

The manipulation of the plate $2 will in to cause the de- --livery ofthe fuel at the requisite'point in the'bath, and the sloping top wall 7,together in the furnace chamber.

the heat units fro the charge and insures a practically complete withthelocation and size of the outlet opening and the proper proportion of thestack and proper regulation of the fuel pressure causesthe flame to hugthe bath closely throughout its length to most effectively heat thebath. In some instances, however, it. maybe preferable to;employ a topblast to augment the'downward delivery of the flame and I have thereforemade provision in my improvement for the employment of such a blast whenrequired. With this en'dgin view, the top Wallof the chamber may bedepressed, as indicatedat 37, directly above or just rearwardly of thebridge wall 11 and v this depressed portion is equipped. with aplurality of downwardly directed blast nozzles 37 through which airunder pressure is delivered from the transversely extending supply pipe38. As previously stated, the top blast may be used if desired, but Ihave found that with iny method, the flame is sufliciently controlledand depressed and a high degree of efliciency is obtained without theemployment of this blast, which has heretofore been consideredindispensable, but has i K I nevertheless been a source of trouble incansing oxidization of metal and interfering with proper control of therelative proportions of fuel and air. troubles is one of the markedadvantages resulting from my present invention.

The elimination of these The rear end -of the furnace chamber isconnected with a properly constructed stack 39 through which theproducts of combustion are discharged and communication is weestablished betweenlthe chamber and this stackpreferably immediatelyabove the reari bridge wall 41 through an opening 42 which 1sproportioned according to 'size'of the furnace and the pressure underwhich the fuel 5 is delivered by the burner nozzles.

It has heretofore been the practice to em-. ploy a large communicatingopening between the furnace chamber and the stack and to induce strongdraft through this opening. result hasbeen that an enormous quantity ofthe. heat units of '"the combustible fuel has "been carried from thefurnace and delivered' to thestack so as to-be lost for effective use.

1 3 y employing a low pressure at the fuel dehvery nozzles, the veloci yof the flame through the furnace is reduced so that its heat' 2 unitsmay be transferred-to the charge.- This desirableefl'ect isfurtherincreased by pro- {port-ioning the connectingopening 42 to the stack andproportioning the stack itself so that astatic pressure is normallymaintained This pressure? is dist nguished from a partial vacuum whichhas heretoforebeeirmaintained'in these fur- 12h naces, greatlyfacilitates the transference .of

the burning mixture :to

combustion of the fuel particles before they leave the chamber,

w he. res lt theat r;

of the furnace.

ifany, unburned fuel particles are wasted through the stack. Obviously,this feature fireatly enhances the efliciency of the furnace.

y regulation of the feed pressure, this static ,pressure maybecontrolled and may be reduced to. a balanced draft or even to anappreciable u draft if desired.

It wil be obvious from theforegoing that in my improved method,thecomminuted, pulverized, atomized, or diffused fuel or fuels,severally. ortwo' or. more collectively, thoroughl mixed with suflicientair tosupp t comp in 'an obliquely downward direction ,and at lowvelocity that ignition and combustion take place close tot e deliver,nozzle. It

shouldbe observed, however, t at the igniv ete combustion, is deliveredin a tur-' bulent, swirling condition'into the furnace establishes twovery desirable factors viz: 1.) complete chemically balanced combustion,and (2) inert gases which cannot do damage to product, furnaces, orheating sur- I faces. 1

Furthermore, a considerable proportion of the slag resulting from flameformation isimmediately deposited in the front pocket beneath the burnerso that it does not mingle with the bath slag, and consequently, not.only ,thequantity of bath slag is reduced,

materially but the character of the slag 1s improved. The flame directedagainst the.

bath being ina turbulent and swirl1ng'condition tends, by reason of itspoint and dlrection' v vof delivery into the bath, and by reason of theflat character of the bath' floor, to pene trate. the .charge of looselypiled solid mation and combustion takes place close to the terial uponthe hearth and'to travel along nozzle, irrespective of the angularposition at which the nozzle is directed intothe fur- .'nace, and it isnot the purpose to limit or restrict this invention in respect of thevari- 1 'ous control features to the combination feature of discharge inan .angular direction. Indeed, it is obvious that the complete perfectcombustion is due to other conditions than the angularity, among thesecontrolling factors being the control ofquantity and delivery of theevenly diffused mixture. of the fuel or. fuels in a turbulent condition.This is irrespective of the angular-ityof delivery with reference, tothe horizontal axis Theangui'ar delivery is of special value in certainparticular processes and is an added feature of advantage in the presentinvention, wherein the process or operatin conditions make its useadvisable.

5o ture is, one of the vital improved features in is known as the resentinvention. .a c emical compound immediately after being released from aformer existing combination is in.- a highly active state which nascentand, therefore, most and complete recombinasusceptible to quick tion. Inthis case it is desired to bind the fuel constituents existing as,nascent hydrocarbons with the oxygen'in chemically balanced proportions,so that the resulting. new

that is the combustion gases, are

mp u s,

possible inert and, hence-inactive as to any chemical reaction whilepassing through the was hati This invention,

1 furnace inv contact with product, walls or therefore,

-of fuel and air and the It 1s well known that the hearth beneaththe'charge so as to expedite the melting of the same. en the charge issurface and because of the fact that the melted, the flame impingesuponits bath is shallow, and of substantially uniform depth, it becomesquickly and uniformly heated and pouring without prolonged operation ofthe furnace, vas is required where the bath floor is deepl depressedso'that the molten metal accumui ates in a des pool. The ra idity of theheating in the urnace' is furt er augmented by the fact that the flameis caused to closely hug thebath throughout its length. This conditionis produced not only by the direction, velocity and manner of the fueldelivery into the furnace, but also by the fact that the rearportions-of the furnace chamber in which the 'products of combustion arecoolest is of progressivel reduced cross sectional area by reason of troof, andfurthermore by the fact that the rear bridge wall is low andthe communicat-. ing-opening with the stack is also low and is soproportioned as is also the stack, that by regulationof the fuelpressure, a slight static pressure may be maintained in the furnace,which is conducive toward com .tion of the most effective transdelivery. with the pulverized fuelitself of sufli'cient' air to supportcomplete combustion. Consequently, an auxiliarysupply'of combustion a1rthrough the walls of the fur- I n'ace is unnecessary, and

of auxiliary cold air into the furnace is not reduced to a conditionsuitable for e downwardly sloping lete combus rence of heat Y t0 thecharge. My method contemplates the in fact, the delivery a c desirablesince it tends to reduce the temperature thereof. The top blast maytherefore be and preferably is entirely eliminated, but

since some types of work seem to be slightly more effectively-performedby additionally depressing the flame through the instrumen-i tality of,a top blast, I have illustrated the application of a top blast to thefurnaceherer in shown.

By the practice of the method above'dia Q fined in t efollowing claims.7

closed, Ianinot only able to reduce the :fuel consumption {and toexpedite the melting, heatin and pouring of the, char e, but also to .emoy -in the composition oft e charge a 'duction of m'etalof aredetermined 0 ar-.

acts; and composition.

1 A nace charge. In practice, I

"betoolow inone bee-regulated to hold the molten mass in staconsi erablygreater proportion-of scrap iron than has heretofore been possible inthe rohis feature is manifestly of significant importance since theproportion .of ig iron required may be diminished, there '37 decreasingthe cost of the furhave found that with my novel method, I am able toutilize, instead of over 60%.expensive'pig iron, high in silicon and.manganese to of scrap which is low in silicon and manganese,-as hasheretofore been customary, considerably more scrap than ig iron in a-charge,-and still obtain a resu tant malleable iron of superior qualitycontaining the reqnisitepredetermined pro rtions of silicon, manga-'nese, carbon an sulphur manganese. I

Should a test of the molten metal show it to ingredient the flame maytus quo with respect to the other ingredients while the requisitequantity of thelow ingre-' dient is added to the charge to produce thedesired analysis. My invention therefore, af

. ,workof the furnace and the cost of'repairsis serviceable forprolonged I It is believed that my invention, of its inherentadvantages, ja nd appreciated from further description, and while anddescribed a ,the me fords, a 'wide range offlexibility in its operationaud t-he results which may be secured thereby." v v Furthermore, byreason of the elimination fromth'e-bath of alar'ge portion of the slagcharacter of the bath slag, asthe result of improved gas conditions fand by improving the in the furnace, thedeterioration of the brick ismaterially decreased,

roportionately diering the furnace periods of time.

and many minished, aswell as ren the fore oing. without have shown forcariging it into e'flect, obviously, both t od andapparatus' may bevaried .within considerable limits without departing from the scopeofthe invention vas defI claim: i.-

IZ 1; Ida furnace, the combination of a heat-a tion and and means fordeliveringa combustible mix-i ing ing chamber. provided with a hearth,sa d hearth being substantially level from end to end, archedslightly'upwardly in cross secadapted to contain a shallow bath,

are oi eomminuted fuel and air to said cham- 2; In a furnace, thecombination of a heat chamber, '-comp'risinga hearth substanproviding arelatially'level from end to end :ji gly shallowbath, an outletstack'comm'u i5 jjca'ting with said chamber, and a rear bridge.

will beunderstood" pre rred methodandmeans b wall between saidbath andstack, the I communion-tin her and stack lation-to the stack and thefeedpressure as to maintain a bar. I v r 3. In a furnace,'the combination ofa heatstatic pressure insaid 'cham Q ning between said chamingproportioned with re- .in chamber, comprising a hearth substantia 1ylevel from end to end, an outlet stack? communicating" with saidchamber, and a rear bridge wall between said bath and "said r stack; thecommunicating opening between I said chamber and stack being so toOrtioned with relation to the stack and the eedjpressure as to maintaina static-pressure in said chamber. I

.4. In a furnace, the combination of a heating chamber, comprisinga-hearth substan-' tially level from end to end and adapted to receive acharge'to be heated, an outlet stack communicating with said chamber,and a rear'bridge wall between said bath and said I stack; thecommunicating opening between I said chamber and stack being so withrelation to the stack and t e eed pressure asto maintain a staticpressure in said chamber. f

5. In a furnace, the combination of a heating chamber, comprisin ashallow bath, an out at stack and a rear wall between-said chamber andstack' ropro or'tioned a hearth providing" I vided witha restrictedopening adapt to maintain a static pressure in saidchamber. 6.121 afurnace-,the combination of'a heat ing chamber, including a hearth,means for chamber, an outlet stack, and 'a -rear;wall between saidchamber and with a restricted opening adapted to main, tain a staticpressurein said chamber? I I 7.;-In a furnace, the combination of aheating chamber, an outlet stack communicating said chamber, sa' chamberand .stack'so proportioned as to maintain a static r. 8.113 afurnace,thecombii'iationof a heating chamber, means for'feedin a air andfuel into'saidbhampressure in the said chamso proportioned new ure inthe said chamber.

stack provided I I I I o ceding a mixture ofair and fuel into said andan opening between r I mixture of a 1' II v an voutlet "stackcommunicating" with said chamber, and i an opening between said chamberand stack tain a. static pres- 9. In a'fur'nace, the combination are iiai' ing chamber,

air and fuel into said chamber, meana for controlling the fuel and ai'rfed, an outlet means for; feeding .a mixtureof stack communicating withsaidcharnber, and

an opening between said chamber and stack so proportlonedas to maintaina static pres-c sure in the said chamber. f; f I

' 10. A furnace, comprising ac'hamber hav; ing front and-rear walls, ahearth, abridge wall spaced from s ai'df I I I clined lipwardly fromsaid -bfiage "wa11; m:

' taining 11 static pressure in ward said front wall and providedadjacent the front wall. with a pocket, and means for delivering amixture of air and comminuted fuel to said .chamber directly over saidpocket.

11. In a furnace, the combination with a chamber provided with a healthand a floor sloping upwardl' and forwardly of said hearth, of means fordelivering to said chamher at low velocity a mixture of comminuted fueland air in a turbulent condition, and a pocket in said floor immediatelybeneath the point of entrance of the mixture into the chamber adaptedtoreceive the slag produced at the point of flame formation in'saidmixture. I v

12. In a furnace, 'the combination of a. chamber comprising front andrear walls,

a hearth, means formaintaining a static pressure in the chamber, meansfor supplying to said chamber in turbulent condition a mixture ofcomminuted fuel and'air, means for varying the direction of discharge tosaid mixture into said chamber, and a slag pocket "disposed adjacent toand beneath the point of entrance of said mixture into'the chamber. 13.The herein described method, which cons'istsin deliveringto a furnacecontaining a charge ofmaterial to be treated, a supply of plulverizedfuel thoroughly mixed with sufcient air to support complete combustion,causing the delivery of such fuel in aturbu-- lent condition and 1n adownwardly inclined direction, separating a portion of the slagresulting from flame formation'and collecting the same at a point remotefrom the'bath, causing the flame to hug the bath, and maintaining astatic pressure in the heating chamber of the furnace.

consists in delivering to-a furnace a supply of fuel thoroughl mixedwith'sufficient air to support comp ete combustion, said fuelbeing)atomized and diffused and delivered in a tur ulent condition,separating a portion of the sla resulting from combustion at the; placeflame formation and maintaining astatic pressure in the heating chamberof the furnace. 3 5 The herein described method, which consists indelivering to a furnace a supply of fuel thoroughly mixed withsufficient air to;

' support com lete combustion, said fuel being atomized an diffused anddelivered in a turbulent condition at lowiv'elocit separating a portionof the sla resulting fiom combustion' at the point of ame formation andmainthe heating chamber of the furnace. 1 k

" m 16. Theyherein described method, which consists indelivering to 'afurnace a supply of f fuel thoroughly mixed with sufficient air tosupport complete co'mbustiom'said fuel being atomized and diffused anddelivered in a i turbulentcondition withcontrolledjvelocity,

14.'The herein described method, which b separatin a portion of the slagresulting from com ustlon at the point of flame formation andmaintaining a static pressurein the heating chamber of the furnace.

- 17. The herein described method which consists in delivering to afurnace controlled total quantities and controlled relative proportionsof air and fuel in a mixture, the said fuel being atomized and diffusedand in free suspension, said mixture being in a turbulent condition withcontrolled velocity, separating a portion of the slag resulting fromcombustion at or near the point of flame formation in the said mixture,and maintaining and controlling a static pressure in the heat- ,80

ing chamber. a

18. The herein described method, which consists in delivering inturbulent condition to a chamber containing a charge of material" to betreated,v a supply of pulverized combustible material at low velocity'thoroughly mixed with suflicient air to. support combustion,causing'the flame from said combustible material to travel in proximityto v the bottom of the char e, and regulating the 0 pressure within saidc amber. Y I 19. The herein described method, which consists indelivering in turbulent condition to a furnace chamber, a supply ofpulverized combustible material at low velocity thoroughly mixed withsuflicient airrto support combustion, and regulating the pressure Withinsaid chamber. p 20. r The herein described method, which consists indelivering in turbulent condition to a furnace chamber, a suppl ofpulverized combustible material thoroug ly mixed with suflicient air tosupport combustion and regulating the static pressure within said cham-21. The herein described method, which consists in delivering controlledquantities and controlled relative proportions of fuel in a turbulentcondition to a furnace chamber, I said fuel beingin free suspension atlow-ivelocity, the said'fuel being thoroughly mixed with suflicient air;to support combustion, and regulating the static pressure within saidchamber. a q

'22. The "herein described method which consists in producinga'malleable -metalo predeterminedcompositionby charging a fur nace withpig iron and scrap, the quantity of scrap being in excess of t e pigiron, and reducing the chargefto malleable iron of a predetermined comition. by subjecting the charge to-a flameo such quality and intensityaswill reduce the charge without losing an appreciable portion o thesilicon and manganese contained in the charge. j v

' 23. The herein described meth d which consists in producing amalleablemetal' of predetermined composition by charging a urnace with pig ironand scrap, the quantity of scrap being n excess. of. the pig ironand I II reducing-the charge to malleable iron of a 7 predetermined compositionby subjecti'ngthe duced.

charge to a flame of such quality and inten-' sity as will reduce thecharge and at the same time maintain control of the carbon, silicon andmanganese contained'in the charge.'

24. The herein described method which c'onsistsin producing a malleablemetal of predetermined composition by charging a furnace with pig ironand scrap, the quantity of scrap being in excess of the pig iron, andreducing the charge to malleable iron' of a predetermined composition bysubject ing'the charge to a flame of such qualit and intensity as willreduce the charge withoutso alterlng' the content of carbon, silicon andmanganese and other ingredients, as to impair the quality. of themalleable iron pro- 25. The herein described method =whiih consist inproducing a malleable metal f predetermined composition by charging ascrapiron 'and subjecting to the act onof a flame of suc intensity aswill reduce the charge without produces flame which will have thedesired; I

' flame both as to-mtens tyand chemical comurnace with pig iron andscrap, the quantity of scrap being in excess of the "pig iron, andreducing the charge to malleable iron of a predetermined composition bysubjecting the charge to a flame of suchv uality and intensity as willreduce the c ar ge without losing such portion of. the carbon, silicon,

manganese, and other ingredients contained.

in the charge as will impair-the quality of the finished product. I

26. The method which consists in deposit-. ing in a furnace a charge ofmetal consisting of less than 50% pig iron and more than said chargequality and appreciable loss 'of: silicon and manganese therebyproducing a high grademalleable' iron. I a

27. The method of treating metals which-1 consists in subjectinga chargeof'metal in a furnace to the action of a'burning turbulent mixture ,ofpulverized fuel and air .deliv ered at low velocity, and controlling'therelative proportions of fuel and air so. as to effect u nthe 'cha r o28. e method of treating. metals which consists in subjecting a chargeof metal in' a furnace to the action of a burning turbulent mixtureofpulverizedfuel and air de-- livered at low velocity, controllingtheveiocit of the ,niixture delivered, and con- 5 trolling the relativeproportions of fuel and air so as to produce a flamewhich will have I llthequantity relative proportions of ,fuel

the desired efiect upon'the charge.

29. The method. of treating metals,1which' consists in subje cti ngacharge of metal in a. furnace to the action of a burning'..tur- 'bulentmixture of'pulverized fuel and air delivered. at. low velocity, andcontrolling furnace to the action of aburnin and air so as to produce aflame which will have the desired effect upon thechar'ge.

a furnace to the action of a burning turbulent mixture of pulverizedfuel and air delivered at low velocity, regulating the relativeproportions of fuel and air and maintaining a static pressure in thefurnace.

' 32. The method of firing which consists in delivering to a furnace aburning'turbuentmixture. or mixtures of fuel and air,

said fuel being diffused in a1r', said fuel being delivered at lowvelocity, regulating the rel- I ative proportions of fuel'and air andmaintaining a static pressurein the'furnace.

33 The method of treatipg'metals', which consists in subjecting a chargeof metal in a furnace to the action of a burning turbulent mixture ofpulverized fuel and air, and. regulat' the static pressure 'in thefurnace.

. '34l lhe method of treating metals, which consists in subjecting acharge of metal. in a furnace to the action f a burning turbulentmixture ofpulverized, fuel and air, and regulating the proportions offuel and airto a neutral flame at 35. The method of treating metals,which consists in subjecting a charge of metal in a g turbulent mixtureof pulverized fuel and air, and regulating the flame to cause theproduction in the metal when poured of the requisite propplrtlilons ofcarbon, silicon, manganese and s p v in to a furnacea burning turbulentmixture thereby produce an oxidizing, a reducing or no 36. The methodwhich'consists in deliver a o pulverized fueland air and regulating theI position of'the' gases so as, to control the "cheinical reaction ofthe on any but in'g surfaces that ma be exposed to the' turbulent notionof v 2 consistsin placinga charge of material in. the suhi s M0 the?action 'of a burning garb- 15 mixture "of pulv r zedfuel. gnaw-anulating the asf-Jflii' ihtensitjz 17,9os i i 13 chemicalcomposition ofits constituent gases so 'as to have the desired chemical effect on thematerial beingtreated.

39. The combination with a heating cham- ,ber provided with a hearthconstructed to contain a shallow bath, ofmeans for delivering atrelatively low velocity to said chamher a swirling turbulent combustiblemixtui'e comprising air with fuel uniformly lo diffused therethrough.

40. The combination with a heating chamber provided with a hearthconstructed to contain a shallow bath, of means for delivering atrelatively low velocity to said cham- 15 ber a swirling turbulentcombustible mix-- ture com rismg air with fuel uniformly difi'used terethrough and means including an adjustable damper for controlling thedelivery of said mixture. T

2o 41. The herein disclosedmethod comprising, producing outside'a-combustion chamber a combustible mixture of fuel uniformly diflusedthroughout suificient air to support complete combustion of said fuel,delivering said mixture in a turbulent condition at low velocity to thecombustion chamber, and regulating the combustion of said mixture withina range including oxidizing and re-i ducing frames. 1 v V 1 an Inwitness of the foregoing I aflix my sig-.

nature. I .MILTON W. ARROWOOD.

